President Donald Trump has claimed that the 2015 Iran nuclear deal was “a road to a nuclear weapon” and the country “would be sitting with a massive nuclear weapon three years ago” if he hadn’t withdrawn the U.S. from the deal in 2018 during his first term. The multilateral deal aimed to restrict Iran’s uranium enrichment program, and experts told us that after the U.S. withdrawal, Iran accelerated it instead.
It’s not possible to predict what would have happened if the agreement, called the Joint Comprehensive Plan of Action and negotiated by former President Barack Obama’s administration, had remained in place. In addition to imposing restrictions on Iran’s enrichment of uranium, the deal required international inspections of the country’s nuclear facilities.
On March 3, when speaking about the U.S. airstrikes on Iran that began Feb. 28, Trump said that Obama “made maybe the worst deal I’ve ever seen, because he gave all power in the Middle East to Iran, he went the exact opposite way, and I terminated that. If I didn’t terminate that deal, they would be sitting with a massive nuclear weapon three years ago, which would have been used already on Israel at least, and other countries also. And we wouldn’t be talking about it right now.”
The president went on to say that Obama “was giving them the right to have the path to a nuclear weapon,” saying that deal “expired.”
The next day, Trump said: “If we didn’t terminate the worst deal, one of the worst deals ever made, the Obama nuclear deal … it was a road to a nuclear weapon. Bad things would have happened four years ago, because they would’ve had a weapon four years ago, if I didn’t terminate that deal.”
And during a speech on March 11, Trump said, “But that deal, the Iran nuclear deal gave them the right to have a nuclear weapon as of three years ago.”
But several experts we spoke to disputed Trump’s claim and told us that Iran advanced its nuclear program after Trump’s decision to pull out of the agreement in his first term.
“Iran was able to advance its nuclear programme to the point where it was before the 12 Day War last June not because of the JCPOA, but because President Trump withdrew the United States from the JCPOA,” Laura Rockwood, senior fellow at the Vienna Center for Disarmament and Non-Proliferation, told us in an email. Rockwood worked for the International Atomic Energy Agency for 28 years, retiring in 2013.
Similarly, Richard Nephew, an international and public affairs senior research scholar at Columbia University who worked as a special envoy for Iran and for the State Department under the Biden administration, told us, “Trump’s decision to withdraw from the JCPOA in 2018 had a significant accelerating effect on the program.”
“The JCPOA would absolutely not have allowed Iran to develop nuclear weapons,” Nephew said. “First of all, there were prohibitions; then there were transparency requirements; and, then, there were the risks of snapback and punishment” if Iran violated the terms.
Daryl G. Kimball, executive director of the Arms Control Association, a nonpartisan organization that provides analysis on arms control and national security issues, told us for an earlier story that the 2015 nuclear deal “established an array of limits on Iran’s uranium enrichment and uranium stockpiling” and a rigorous monitoring and verification program. After the Trump administration’s withdrawal from the deal, “Iran began to reconstitute its nuclear capabilities, including by deploying large numbers of advanced centrifuges and stockpiling” highly enriched uranium.
As we’ve explained before, the nuclear agreement, which took effect in 2016 and was signed by the five permanent members of the United Nations Security Council — China, France, Russia, the United Kingdom and the United States — and Germany, restricted Iran’s ability to enrich uranium for 15 years and required monitoring and inspections of Iranian facilities for the same amount of time.
Under the deal, Iran agreed to do away with much of its nuclear program and, in exchange, the signatories lifted sanctions, the Council on Foreign Relations explained.
Trump announced on May 8, 2018, that the U.S. would withdraw from the deal and reinstitute sanctions. About a year later, in July 2019, Iran had exceeded the limits on its stockpile of low-enriched uranium that had been set in the JCPOA, the International Atomic Energy Agency reported at the time. Iran’s foreign minister said the country would begin to enrich uranium beyond the low level allowed under the deal (3.67%), which was the level needed for civilian nuclear power.
“The JCPOA dramatically restricted Iran’s ability to produce fissile material and, in particular, not only placed a cap on the quantity of enriched uranium Iran could stockpile and on the level of enrichment, but required the dismantlement of 2/3 of its centrifuges and limited its ability to produce advanced centrifuges,” Rockwood said. “Iran simply would not have been able to enrich to the point of possessing over 400 kg of 60% enriched uranium had the JCPOA remained in place.”
Rockwood was referring to the amount of 60% enriched uranium that Iran had stockpiled before the June 2025 U.S. bombing of nuclear program sites in the country. To be weapons-grade, the uranium would need to be enriched to 90%, as we’ve explained.
Of course, Iran could have violated the terms of the nuclear deal and pursued a nuclear weapon.
“No single element blocks Iran’s pathway to nuclear weapons, but taken together, the nuclear restrictions and monitoring form a comprehensive system that will put nuclear weapons out of Iran’s reach for at least 15 years,” the nonpartisan Arms Control Association explained in an August 2015 analysis. “Many of the JCPOA provisions also extend beyond 15 years. Monitoring of centrifuge production facilities continues for 20 years, and monitoring of uranium mines and mills continues for 25 years. International Atomic Energy Agency (IAEA) inspectors will have enhanced access indefinitely.”
Critics of the JCPOA — including Trump — have argued that the deal didn’t go far enough, and they objected to the lifting of economic sanctions.
“One of the main arguments used against the JCPOA was that it allowed Iran to continue enriching uranium and move closer to nuclear capability while remaining technically in compliance,” the nonpartisan Center for Arms Control and Non-Proliferation wrote in a June report. “The JCPOA also contained so-called ‘sunset provisions’ on various aspects of the deal such as lifting limits on centrifuges after 10 years or reduced enrichment beyond 3.67% only lasting for 15 years. This led to concerns that the deal would only temporarily delay Iran’s nuclear program while preventing parties from finding a more permanent solution. Additionally, critics worried that lifting sanctions on Iran in return for the JCPOA’s focus on constraining Iran’s nuclear program would diminish the United States’ ability to address other security concerns such as Iran’s missile program or its funding of violent non-state groups in the Middle East.”
In saying that Iran would’ve had a nuclear weapon “three years ago,” Trump may have been referencing one of these provisions, known as “transition day,” which was set to take effect on Oct. 18, 2023, eight years after implementation of the deal. On that day, if Iran had complied with its commitments under the deal, some of the restrictions on Iran’s nuclear and missile programs would have been lifted. However, while U.N. restrictions expired, countries that remained in the JCPOA after the U.S. withdrawal chose to maintain their restrictions, citing Iran’s noncompliance.
We asked the White House about Trump’s remarks, but we didn’t get a response.
While Trump claims that the JCPOA would have brought Iran closer to having a nuclear weapon and his withdrawal stopped that, the Center for Arms Control and Non-Proliferation estimated that the withdrawal sped up the so-called “breakout time,” or the time Iran would need to produce weapons-grade uranium that could then be used for one bomb – if the country chose to do so. The center estimated, as of November 2024, that the breakout time went from two to three months before the deal to 12-plus months during the deal. And then, after the U.S. withdrawal, the breakout time was reduced to just a couple of weeks.
As we’ve explained, it would take more time to actually develop a nuclear weapon. “After this point, once you have the weapons-grade uranium, Iran would then need to manufacture the rest of the weapon. This process would likely take much longer, perhaps months to a year,” Emma Sandifer, program coordinator at the Center for Arms Control and Non-Proliferation, told us for an earlier story.
She said that last June’s airstrikes likely lengthened the “breakout time,” but the IAEA hasn’t been able to inspect the damaged nuclear program sites since then.
In 2017, several months before withdrawing from the nuclear deal, Trump had claimed that Iran “has committed multiple violations of the agreement.” But as we wrote at the time, the IAEA said in its multiple reports after the deal went into effect that Iran was abiding by it. Trump himself had twice certified to Congress that Iran had complied with the deal, before claiming there had been violations.
In late September 2017, Gen. Joseph Dunford, then the chairman of the Joint Chiefs of Staff, told Congress that “Iran is adhering to its JCPOA obligations” and that the agreement “has delayed Iran’s development of nuclear weapons.”
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